1. Field of the Invention
The present invention relates to a method of manufacturing a laminated ceramic electronic component for use as, for example, an inductor, an LC component, a laminated capacitor, a laminated circuit module or other suitable electronic component. More particularly, the present invention relates to a method of manufacturing a laminated ceramic electronic component which has an internal conductor and an internal electrode (hereinafter collectively referred to as the internal conductor), and to a method of manufacturing such a laminated inductor having an internal electrode with a greatly increased thickness.
2. Description of the Related Art
Known laminated inductors are formed by using a sintered body obtained by integrally sintering a metal and a ceramic. When manufacturing the known laminated inductor, a through hole is formed in a ceramic green sheet for electrically connecting one internal electrode provided on the ceramic green sheet to another internal electrode provided under the same ceramic green sheet. Then, internal electrode paste for forming a coil conductor is printed on the ceramic green sheet. The plurality of ceramic green sheets obtained in the above-described manner is laminated, and a suitable number of plain ceramic green sheets are laminated on the top and bottom surfaces thereof. Accordingly, a green laminated body is obtained and is compressed in the thickness direction. Then, by sintering the compressed green laminated body, a ceramic sintered body is obtained. On the outer surface of the ceramic sintered body, a pair of external electrodes is provided and is electrically connected to the coil conductor.
When using the laminated inductor, the number of windings of the coil conductor can be increased by increasing the number of laminated ceramic green sheets. Accordingly, a large inductance is obtained.
To reduce the series resistance of the laminated inductor, it is necessary to increase either the thickness or the width of the coil conductor. However, when applying the above-described method for forming an internal electrode such as a coil conductor where internal electrode paste is screen-printed on a ceramic green sheet, it is difficult to form an internal electrode having a large thickness by one printing process.
Further, when the width of the coil conductor is increased to reduce the series resistance, the inductance deteriorates.
The above-described problems are common to known laminated ceramic electronic components such as a laminated ceramic capacitor, other than the laminated inductor.
In order to overcome the above-described problems, preferred embodiments of the present invention provide a method of manufacturing a laminated ceramic electronic component having an internal conductor with greatly increased thickness.
Preferred embodiments of the present invention provide a method of manufacturing a laminated inductor, which has a coil conductor that functions as an internal electrode and that has thickness which is easily increased, and in which a large inductance and a low series resistance is obtained.
According to a preferred embodiment of the present invention, a method of manufacturing a laminated ceramic electronic component includes the steps of preparing a first ceramic green sheet, at least one second ceramic green sheet, and transfer materials each having a conductor layer on one surface of a carrier film, transferring the plurality of conductor layers onto at least one of the upper surface and the lower surface of the first ceramic green sheet such that the conductor layers overlay one another to form a conductor having the plurality of conductor layers, laminating at least one second ceramic green sheet onto the conductor to form a green laminated body, and firing the green laminated body to form a sintered body.
Generally, when a conductor is formed on a carrier film by a known method such as screen printing, the thickness of the obtained conductor is about 200 xcexcm. On the other hand, a conductor obtained according to the above-described preferred embodiment of the present invention includes a plurality of conductor layers. Subsequently, a laminated ceramic electronic component, which includes a conductor having a low series resistance and which achieves a large inductance and a large current-carrying capacity, is provided.
Preferably, in the method of manufacturing a laminated ceramic electronic component, one of the first ceramic green sheet and the second ceramic green sheet is formed as a composite sheet. The composite sheet may have a connecting conductor that penetrates both surfaces thereof, and the other may be a plain ceramic green sheet. By using the first ceramic green sheet and the second ceramic green sheet, a conductor which includes the plurality of conductor layers that is electrically connected to the connecting conductor of the composite sheet is formed. Subsequently, a laminated ceramic electronic component which has the conductor in a ceramic sintered laminated body formed with the second ceramic green sheets is provided.
According to another preferred embodiment of the present invention, a method of manufacturing a laminated ceramic electronic component includes the steps of preparing at least one ceramic green sheet, a composite sheet having a connecting conductor that penetrates both surfaces of a ceramic green sheet, and transfer materials each having a conductor layer that is to be connected to the connecting conductor on one surface of a carrier film, transferring the plurality of conductor layers onto the composite sheet such that the conductor layers overlay one another to form a conductor which is connected to the connecting conductor and which has the plurality of conductor layers, laminating the at least one ceramic green sheet onto the conductor to form a green laminated body and firing the green laminated body to form a sintered body. Subsequently, a conductor which has a large thickness and which is electrically connected to the connecting conductor is formed, as in the previous preferred embodiment of the present invention described above. Accordingly, as in the previous preferred embodiment, a laminated ceramic electronic component which includes a conductor having a low series resistance and which achieves a large inductance and a large current-carrying capacity is provided.
Preferably, the method of manufacturing a laminated ceramic electronic component further includes the step of laminating the conductor on the upper surface and the lower surface of the composite sheet such that one of these conductors is electrically connected to the upper portion of the connecting conductor and the other conductor is electrically connected to the lower portion of the connecting conductor. Subsequently, the conductors on the upper and lower surface of the composite sheet are electrically connected via the connecting conductor.
According to another preferred embodiment of the present invention, a method of manufacturing a laminated ceramic electronic component includes the steps of preparing a plurality of first ceramic green sheets, a second ceramic green sheet having a connecting conductor that penetrates both surfaces thereof, a plurality of transfer materials each having a conductor layer on one surface of a carrier film, transferring one of the conductor layers onto one surface of one of the first ceramic green sheets by applying pressure, and transferring the other conductor layer thereon by applying pressure such that the conductor layers overlay one another, laminating the second ceramic green sheet onto the conductor layers that are transferred onto the first ceramic green sheet such that the connecting conductor is connected to the conductor layers, transferring the other conductor layer onto the second ceramic green sheet by applying pressure such that the connecting conductor is connected to the conductor layer, and transferring the other conductor layer thereon by applying pressure such that the conductor layers overlay one another, and laminating the other first ceramic green sheet onto the second ceramic green sheet to form a green laminated body and firing the green laminated body to form a sintered body.
According to another preferred embodiment of the present invention, a method of manufacturing a laminated inductor includes the steps of preparing a composite sheet having a connecting conductor that penetrates both surfaces of a ceramic green sheet, transfer materials each having a coil conductor layer that is to be connected to the connecting conductor on one surface of a carrier film, and at least one plain ceramic green sheet, transferring the plurality of coil conductor layers onto the composite sheet such that the coil conductor layers overlay one another to form a coil conductor which is electrically connected to the connecting conductor and which has the plurality of coil conductor layers, laminating the at least one plain ceramic green sheet onto the coil conductor to form a green laminated body, and firing the green laminated body to form a sintered body. Accordingly, a laminated inductor which includes a coil conductor having a large thickness and which achieves a low series resistance and a large inductance is provided.
Preferably, the method of manufacturing a laminated inductor further includes the steps of transferring the plurality of coil conductor layers of the transfer materials onto the upper surface of the composite sheet and transferring the other plurality of coil conductor layers of the transfer materials onto the lower surface of the composite sheet. Subsequently, a first coil conductor is formed on the connecting conductor and a second coil conductor is formed under the connecting conductor. Since the first conductor and the second conductor are electrically connected via the connecting conductor, the obtained laminated inductor achieves an increased inductance.
Preferably, by the method of manufacturing a laminated inductor, the first coil conductor and the second coil conductor are formed to wind in the same direction. Accordingly, the obtained laminated inductor achieves a greatly increased inductance.
Other features, elements, characteristics and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments thereof with reference to the attached drawings.